Modular hollow block structure

ABSTRACT

A modular hollow block structure ( 1 ) includes: a plurality of hollow block members ( 2 ) made by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes ( 4 ) passing transversely through the hollow block members ( 2 ); and at least one connecting post ( 6 ) passing through the cylindrical holes ( 4 ) in adjacent hollow block members ( 2 ), and that includes a securing device ( 8 ) whereby it can be secured to the hollow block members ( 2 ) once fitted.

TECHNICAL FIELD

The present invention relates to a modular hollow block structure, and a method of manufacturing the modular hollow block structure. In particular the invention relates to a modular hollow block structure applicable to floating structures, such as used in oyster and mussel farms, fish farms, floating jetties, floating docks, and the like, or for use on soft wetlands, where a stable platform is required, such as for a temporary road, or to a modular hollow block structure that can be used for example as a stop bank in land or reef stabilization, or for retaining walls, steps, and building foundations, or for liquid storage, and a method of manufacturing and assembling the modular hollow block structure. However, it is to be understood that the invention is not to be limited as such. Moreover, because the invention may have many other applications, the prior art and possible applications of the invention discussed below are given by way of example only.

BACKGROUND ART

A variety of modular hollow block structures, have been proposed for some of the above applications. In particular where the hollow blocks constitute a floating structure.

For example, U.S. Pat. No. 3,983,830 discloses a modular barge and method of assembling, for use on surfaces which may be unstable, such as on an ice flow, for use with oil drilling equipment. In this barge, modular floating sections are attached together using alignment pins, and tensioning cables which clamp the segments together to give a rigid platform.

U.S. Pat. No. 5,4060,114 discloses a float for dock construction with floats connected together in a stacked configuration with rods passing vertically through longitudinally spaced cylindrical holes (tubular posts 50 (column 4 line 11)) formed in rotationally moulded floats 10. The floats may also be connected together front to rear by means of a bottom board which also serves to space the float bottom wall from a supporting surface when the float or dock structure of which the floats are a part, is dragged across the ground. Furthermore the floats may be connected side by side or end to end by way of decking which is supported on top of the floats. This connection between floats is either by a vertical rod passing through the floats, or by members attached to the outside surface of the floats.

German patent DE2000757 discloses a float structure with individual floats that are connected together with rods, and provided with corresponding longitudinally spaced ball and sockets on adjacent sides to transfer the load between floats, while allowing tilting of the floats relative to each other.

French patent FR2597826 discloses a modular float and method for assembling a plurality of such floats in order to form a floating device. The floats are connected together with tubular metal members, and the floats are fixed relative to each other by an elongate member which is located in channels on adjacent sides of the floats. The floats are made for example from sheet metal or plastic sheet bent to provide a channel shape, with a bottom section filled with foam.

In all of the above configurations the floats are connected together with metal cables, rods, or tube members. This variety of components, adds to the complexity of the structure, and the different materials deteriorate at different rates, making maintenance complicated and expensive. Moreover the inventory of different parts adds to the cost of manufacture. Furthermore some of the connection methods do not lend to simple lengthwise, widthwise, and depthwise expansion of the structure to suit different applications.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a modular hollow block structure that addresses the aforementioned shortcomings of conventional hollow block structures, or which at least provides the public with useful choice.

In the following description, cylindrical hole refers to a hole in the form of a cylinder or prism of optional cross-section, i.e. circular, oval, hexagonal, rectangular, or square. Right parallelepiped shape refers to a parallelepiped shape with major planes of adjacent sides (through adjacent corner edges) at right angles to each other. Hollow block member refers to a hollow right parallelepiped member with closed ends.

According to one aspect of the present invention there is provided a modular hollow block structure including: a plurality of hollow block members made by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block members; and at least one connecting post made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section, that passes through the cylindrical holes in adjacent hollow block members, and that includes a securing device whereby it can be secured to the hollow block members once fitted.

With such a construction, the connecting post serves as both an alignment device and a securing device, enabling simple connection of the hollow block members. Moreover, since the connecting post is made by rotational moulding, the manufacture of the hollow block structure can be simplified. Furthermore, having plastic materials for both the hollow block members and the connecting post means that the components will deteriorate at similar rates, facilitating maintenance.

The securing device may comprise any suitable device whereby the hollow block members can be secured together by the connecting post.

For example, the securing device may be achieved by forming the connecting post to have a close fit inside the cylindrical holes to provide a friction engagement.

In another aspect the securing device may be achieved by forming the connecting post to have a close fit inside the cylindrical holes, and expanding the connecting post once fitted into the cylindrical hole by increasing the pressure thereinside to give an interference fit. Pressurization may be achieved by pumping a gas such as air into the connecting post, to a pressure of 200 psi, depending on requirements.

In this case, the connecting post would be provided with an aperture for pressurizing the connecting post once fitted, and with a device for sealing the aperture. The sealing device may be a valve such as used on car tyres. Moreover, sealing of the aperture may be achieved by friction spinning and sealing a plastic plate over the aperture region. This may involve pressing the plastic plate against the aperture region until the plastic melts due to friction, at which time the plate seizes against the aperture region and bonds to provide a permanent closure.

Alternatively the securing device may be achieved by forming the connecting post to have a close fit inside the cylindrical holes, and contracting the connecting post prior to fitting in the cylindrical hole and allowing the connecting post to expand once fitted into the cylindrical hole to give an interference fit.

In this case, the connecting post would be provided with an aperture for evacuating the connecting post prior to fitting, and with a device for sealing the aperture once the connecting post has been fitted and allowed to expand. Again, the sealing device may be a valve such as used on car tyres. Moreover, sealing of the aperture may be achieved by friction spinning and sealing as described above for the pressurized connecting post.

Furthermore the securing device may include a pin or wedge which is fitted into a socket in the connecting post once the connecting post has been fitted between the hollow block members, the socket being provided at a predetermined position in the connecting post to retain the connecting post and block members in a desired connected condition. The hollow block member may also be provided with a socket so that the pin or wedge can be passed through both the block member and the connecting post to retain the connecting post and block members in a desired connected condition. In the case where a pin is used, this may be passed through both side faces of the hollow block member, and if required, can also be used to join corresponding stepped ends of connecting posts.

Moreover the securing device may include an enlarged one end of the connecting post and a threaded portion and lock member on the other end, the configuration being such that the lock member can be threaded to the threaded portion and tightened after assembly, to hold the hollow block members together.

Furthermore, instead of the enlarged one end of the connecting post, both ends may have a threaded portion and lock member.

The threaded portion may be in the form of a female threaded portion on the end of the connecting post, and the lock member may be in the form of a stud which threads into the female threaded portion. Alternatively the threaded portion may be in the form of a male threaded portion on the end of the connecting post, and the lock member may be in the form of a nut threaded thereon.

The threaded portion may be either a male or female threaded portion on one connecting post and a corresponding female or male threaded portion on another connecting post, configured so that the connecting posts can be connected together by threading the corresponding male and female threaded portions to each other, to provide different length connecting posts.

Moreover in the case of a female threaded portion on the end of the connecting post, there may be provided a male thread connector, and two of the connecting posts may be connected together by threading the female threads onto opposite ends of the male thread connector to provide different length connecting posts.

The rotationally moulded connecting post may be any suitable rod like member which can be passed through the holes in the hollow block members. Use of rotational moulding facilitates the forming of a threaded portion in the case of a threaded portion and lock member configuration, since the threaded portion can be easily made to any suitable size (pitch, diameter).

The connecting post may be any suitable cross-section shape which can be fitted through the holes in the hollow block members. For example this may be circular, oval, spline, or rectangular (square).

In the case of a non-circular cross-section shape, one or more of the cylindrical holes in the hollow block members may be made in a cross-section shape complementary to the non-circular cross-section shape of the connecting post, the configuration being such that the hollow block members can be set at a desired angle relative to each other, and maintained in that position by the fit between the connecting post and the complementary cylindrical hole in the hollow block member. Such a feature may be advantageous where certain sections of the hollow block structure are to be kept in relative positional alignment. Moreover, this may be desirable when the hollow block members are held together by just one connecting post, which, if circular, would not prevent relative rotation of the members.

As another device to provide relative positional alignment between the hollow block members, the block members may be formed with recesses around the cylindrical holes, and there may be provided a separate alignment block which fits over the connecting post, and fits into the recesses in adjacent hollow block members.

Preferably the connecting posts are hollow right parallelepiped shape.

In the case of hollow right parallelepiped shape connecting posts, the corner edges may be rounded to prevent catching on the internal corners of the cylindrical holes in the hollow block members, and to allow easy insertion. Moreover, one or more of the connecting posts may be formed with channels on opposite side faces which can be used to take a strap wrapped lengthwise around the connecting post. The strap can then be used to pull the connecting posts into the cylindrical holes in the hollow block member when fitting the connecting posts.

One or more of the hollow block members may further include a plurality of vertical cylindrical holes of optional cross-section. Such vertical holes may be used for supporting vertical hand rail posts or the like. Moreover, the vertical holes may be provided adjacent to opposite edges of the hollow block members and used as a tie device for securing hollow block members together, by threading bands therethrough to secure the adjacent hollow block members together. In this case the adjacent hollow block members would be prevented from pivoting relative to each other. Furthermore, the vertical cylindrical holes may be configured similarly to the transverse cylindrical holes, to take similar connecting posts.

The modular hollow block structure may include at least four hollow block members, with two hollow block members aligned end to end, and two hollow block members arranged on opposites sides of the end to end hollow block members so as to clamp the end to end hollow block members from opposite sides with their transverse cylindrical holes aligned, and with at least one connecting post passing through each of the end to end hollow block members, and the adjacent side hollow block members.

With such a construction, provided the connecting posts are a loose fit in the cylindrical holes, or are circular in cross-section, the end to end hollow block members can pivot about the cylindrical connecting posts to conform to the surface of the land or swamp when in use.

In the modular hollow block structure, at least two of the hollow block members may have more than two transverse cylindrical holes of optional cross-section, and at least one connecting post may be inserted through the cylindrical holes, to lock the hollow block members and prevent relative pivoting.

With such a configuration, it is possible to assemble a hollow block structure with predetermined rigidity over certain areas, such as for the case where the structure is used for making a road over swamps, with some parts able to pivot to conform to the surface, and some parts fixed to provided a rigid base.

In the modular hollow block structure, at least one of the hollow block members may be formed with a curved up bottom surface at one end to form a bow or stern shape.

With such a configuration, the hollow block structure can be made in a seaworthy configuration for use moored in a flowing river, or for use as a vessel which is towed through water or over a soft surface, or a similar application. Alternatively, the ends of the hollow block members may have an attachment device such as a socket, and an end member of desired shape, such as to give streamlining, may be fitted across the end of the modular hollow block structure.

The right parallelepiped shape hollow block members may be formed in any suitable cross-section shape, provided that the major planes through adjacent corner edges are at right angles to each other. For example, the cross-section shape of individual hollow block members may be rectangular or square to suit their application.

In a preferred embodiment the hollow block members are formed with an I-shape cross-section with the arms of the I-shape of the same depth or different depths. Having a bottom arm of the I-shape deeper than a top arm of the I-shape may be an advantage in that the depth can be such that the hollow block member can float with the water line below the top edge of the bottom arm, thereby ensuring a smooth bottom surface which can be easily cleaned of weed and barnacles, etc. Moreover, a thinner top arm may enable a simpler configuration for attaching the hollow block members together, and for fitting the vertical hand rail posts.

In another embodiment, the cross-section shape may be symmetrical about orthogonal central longitudinal planes, with all four side faces of equal width and formed with channel sections, giving a substantially square cross-section. Providing channel sections in all four side faces improves the rigidity of the hollow block members. Moreover, the channel sections may be used for accommodating decking in the case where the hollow block members are used in a pontoon structure or the like.

According to another aspect of the present invention, the modular hollow block structure may include a selective fill and drain device whereby one of more of the hollow block members can be selectively filled or drained via a connecting post.

With such a construction, one or more of the hollow block members may be filled with liquid or the liquid drained, by supplying or draining liquid via the appropriate connecting post connected to the fill or drain hole. This may be desirable in cases where the modular hollow block structure is used as a floating dock, for adjusting the buoyancy, or for the case where the hollow block structure is used for storing different liquids (for example, fuel, chemicals, water, and the like).

The selective fill and drain device may comprise any suitable configuration whereby one of more of the hollow block members can be selectively filled or drained via a connecting post. For example this may comprise individual connecting tubes connected directly to a hollow block member or members which is/are to be filled or drained. The connecting tubes for filling and draining may be supplied with liquid from a manifold, and there may be provided venting tubes connected to a separate manifold, for venting air from or into the hollow block members being filled or drained. In the case of an application where the hollow block members are not fully submerged, air can be vented into the hollow block members simply though an above water opening in the hollow block members, rather than through the venting tubes.

Preferably the selective fill and drain device includes: a fill hole in at least one of the hollow block members adjacent to at least one cylindrical hole in the hollow block member, and a vent hole in the hollow block member adjacent to at least another cylindrical hole in the hollow block member; a fill or vent hole in at least two of the connecting posts arranged to correspond to the fill hole or the vent hole; connecting tubes connected between respective fill or vent holes in the hollow block member and in the connecting posts, and configured so as to enable filling or venting of the hollow block member via the connecting posts; and an aperture in each of the connecting posts to allow filling of liquid therethrough, or venting of air therefrom. In this configuration the arrangement and construction should be such that when the modular hollow block structure is assembled together with the hollow block members secured together with the connecting posts, liquid can be supplied via the aperture through the fill hole into the hollow block member, and air can be vented therefrom, or liquid can be drawn out from the hollow block member via the aperture, and air can be vented thereinto.

With such a construction, hollow block members can be selectively filled or drained by selecting an appropriate connecting post through which to supply or drain a liquid. Moreover, any hollow block member can be easily configured for filling and draining by simply connecting the connecting tubes between the fill or vent holes in the appropriate connecting posts and hollow block members. Having a selective fill and drain device may be desirable in cases where the modular hollow block structure is used as a floating dock, for adjusting the buoyancy, or for the case where the hollow block structure is used for storing different liquids.

According to another aspect of the invention there is provided a method of manufacturing a modular hollow block structure as described above including the steps of: making a plurality of hollow block members by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block members: and passing at least one connecting post made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section through the cylindrical holes in adjacent hollow block members, and securing the connecting post to the hollow block members once fitted.

In the above method, the step of securing the connecting post may comprise: drawing a vacuum inside the connecting post through an aperture, to reduce the outer dimension thereof; inserting the connecting post into the cylindrical hole in the hollow block member; removing the vacuum inside so that the connecting post expands, and sealing the aperture.

Alternatively, in the above method, the step of securing the connecting post may comprise: inserting the connecting post into the cylindrical hole in the hollow block member; increasing the pressure inside the connecting post by filling a gas under pressure through an aperture to increase the outer dimension thereof; and sealing the aperture.

According to another aspect of the invention there is provided a method of manufacturing a modular hollow block structure as described above further including the steps of: connecting together two or more connecting posts having complementary threaded portions at opposite ends, by threading the ends together to make a connecting post of a desired length, and passing the resultant connecting post through the cylindrical holes in adjacent hollow block members, and fitting a securing device to secure the adjacent hollow block members together.

In the above method, at least one of the connecting posts may be formed with channels on opposite side faces, and the method may include the step of wrapping a strap around the sides and one end of the connecting post and pulling from an opposite end to draw the connecting post into the cylindrical hole.

According to yet another aspect of the invention there is provided a method of manufacturing a hollow block member for a modular hollow block structure as described above including the steps of: making a mould to produce a hollow right parallelepiped shape hollow block member, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block members: pouring polyethylene moulding powder into the mould and rotating the mould while heating to form the plastic over the entire inner surface of the mould; and allowing the mould to cool while rotating so that the plastic sets into the shape of the hollow block member, and then removing the hollow block member from the mould.

According to yet another aspect of the invention there is provided a method of manufacturing a connecting post for a modular hollow block structure as described above including the steps of: making a mould to produce a hollow cylindrical connecting post of a desired cross-section shape; pouring polyethylene moulding powder into the mould and rotating the mould while heating to form the plastic over the entire inner surface of the mould; and allowing the mould to cool while rotating so that the plastic sets into the shape of the connecting post, and then removing the connecting post from the mould.

By manufacturing the hollow block members, and the connecting posts by rotational moulding, various shapes for the hollow block members and connecting post can be easily manufactured. Moreover, by making the components from the same plastic material, costs for the parts can be kept down.

Moreover, the invention also provides a method of selectively filling and draining a modular hollow block structure as described above including the step of: providing a selective fill and drain device whereby one of more of the hollow block members can be selectively filled or drained via a connecting post.

This invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of the parts, elements or features, and where specific integers are mentioned herein which have known equivalents, such equivalents are deemed to be incorporated herein as if individually set forth.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a modular hollow block structure according to an embodiment of the present invention;

FIG. 2 shows details of sealing an aperture region by a valve and subsequent friction spinning and sealing a plastic plate over the aperture region;

FIG. 3 shows details of a method of attaching and aligning hollow block members to give greater strength and rigidity.

FIG. 4 is a plan view of various hollow block structures according to embodiments of the present invention, FIG. 4A being a two hollow block configuration, FIG. 4B being a linked hollow block configuration, and FIG. 4C being a platform hollow block structure;

FIG. 5 is a cross-section on A-A of FIG. 4A, FIG. 5A illustrating two hollow block members connected by a connecting post, and FIG. 5B illustrating an embodiment of a connecting post where two connecting posts are connected together to give a longer connecting post;

FIG. 6 is a perspective view of a hollow block member according to an embodiment of the invention;

FIG. 7 is a schematic diagram of a floating dock configuration being an example of an application of the modular hollow block structure of the invention, FIG. 7A being a side view with a boat outline shown dotted, and FIG. 7B being a perspective view;

FIG. 8 illustrates a method of connecting hollow block members together to form the floating dock structure of FIG. 7; and

FIG. 9 shows details of a selective fill and drain device applicable to the modular hollow block structure of the present invention. FIG. 9A is a schematic plan view showing connection positions for fill or drain holes, and vent holes, and FIG. 9B is a schematic perspective view showing details of fill, drain, or vent holes in the hollow block members, and fill, drain, or vent holes in the connecting posts, and the arrangement of respective connecting tubes.

BEST MODES FOR CARRYING OUT THE INVENTION

Preferred embodiments of a modular hollow block structure according to the present invention are described below with reference to FIG. 1 through FIG. 9.

FIG. 1 shows a perspective view of a modular hollow block structure according to an embodiment of the present invention.

As shown in the FIG. 1, the modular hollow block structures 1 comprises: a plurality of hollow block members 2 made by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes 4 of optional cross-section (square cross-section in this embodiment) passing transversely through the hollow block members 2; and a plurality of connecting posts 6 made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section (square cross-section in this embodiment), that pass through the cylindrical holes 4 in adjacent hollow block members 2, and that include securing devices whereby they can be secured to the hollow block members 2 once fitted.

In this embodiment, the hollow right parallelepiped shape hollow block members 2 have a symmetrical cross-section shape about orthogonal central longitudinal planes, with all four side faces of equal width and formed with channel sections 9 and rounded edges 7, giving a substantially square cross-section. Providing the channel sections 9 in all four side faces improves the rigidity of the hollow block members 2. Moreover, the channel sections 9 may be used for accommodating decking in the case where the hollow block members 2 are used in a pontoon structure or the like. Some or all of the hollow block members may have a substantially rectangular cross-section rather than a substantially square cross-section depending on requirements.

In this embodiment several different securing devices 8A to 8E are shown for illustration. However, in practice it is envisioned that only one or two types of securing device would be used.

Here securing device 8A is achieved by forming the connecting post 6 to have a close fit inside the cylindrical holes 4 to provide a friction engagement.

Securing device 8B is achieved by forming the connecting post 6 to have a close fit inside the cylindrical holes 4, and expanding the connecting post 6 once fitted into the cylindrical hole 4 by increasing the pressure thereinside to give an interference fit. Expansion is by means of an aperture 10 for pressurizing the connecting post 6 once fitted, and with a device such as a tyre valve 12 (not visible in the figure) for sealing the aperture. After pressurizing, the aperture region is sealed by friction spinning and sealing a plastic plate 14 over the aperture region. Details of this method of sealing are given later with reference to FIG. 2.

Securing device 8C is achieved by forming the connecting post 6 to have an interference fit inside the cylindrical holes 4, and contracting the connecting post 6 prior to fitting in the cylindrical hole 4 and allowing the connecting post 6 to expand once fitted into the cylindrical hole 4 to give the interference fit. Contracting is by means of an aperture for evacuating the connecting post 6 prior to fitting, and with a device such as a tyre valve for sealing the aperture once the connecting post 6 has been fitted and allowed to expand. After allowing the connecting post 6 to expand, the aperture region is sealed by friction spinning and sealing a plastic plate 14 over the aperture region, in a similar manner to with securing device 8B.

Securing device 8D (see detail A in FIG. 1), includes a pin or wedge 16 which is fitted into a post socket 18 in the connecting post 6 once the connecting post 6 has been fitted between the hollow block members 2. The socket 18 is provided at a predetermined position in the connecting post 6 to retain the connecting post 6 and the hollow block members 2 in a desired connected condition. In this configuration, a second pin or wedge 16 is fitted to the other end of the securing post 6 (not visible in the figure), so that the hollow block members 2 are clamped together by the pin or wedge 16. In the case of a wedge 16, the taper of the wedge would ensure more secure clamping of the hollow block members 2.

In securing device 8E the hollow block member 2 is also provided with a socket 20 so that a short pin 17 can be passed through both the hollow block member 2 and the connecting post 6 to retain the connecting post 6 and the hollow block members 2 in a desired connected condition. As shown in detail B (a) of FIG. 1, the socket 20 in the hollow block member 2 need not pass completely through the hollow block member 2, provided the hollow block member 2 and the connecting post 6 can be securely located relative to each other by the short pin 17. In detail B (a) of FIG. 1, the short pin 17 is shown passing through one side face of the hollow block member 2 and into the socket 20 formed in one side face of the connecting post 6. In detail B (b) of FIG. 1, a long pin 17 a is shown passing through both side faces of the hollow block member 2 and completely through corresponding stepped ends of two connecting post 6. This configuration is used where two connecting posts 6 are to be joined. Once fitted into the socket 20, or through both side faces of the hollow block member 2, the pin 17 or 17 a is secured in place by placing a plastic plate 15 over the top of the pin 17 or 17 a and friction welding the plastic plate 15 to the hollow block member 2.

Similar securing devices 8A to 8D are also provided for securing the vertically stacked hollow block members 2, as required. Moreover, a threaded securing device such as described later with reference to FIG. 5 may be used.

As shown in FIG. 1, the connecting posts 6 are formed with rounded edges 22 to facilitate insertion into the cylindrical holes 4 in the hollow block members 2 (only one vertical post shown as an example). If desired, to further facilitate insertion of the connecting posts 6, these may be formed with a channel 24 (see securing device 8E) on opposite side faces to take a strap, which can be wrapped around the sides and one end of the connecting post 6 and pulled from the opposite end to draw the connecting post 6 into the cylindrical hole 4.

FIG. 2 illustrates a method of sealing the aperture region of the connecting post 6 by a valve and subsequent friction spinning and sealing a plastic plate 14 over the aperture region. FIG. 2A shows the plastic plate 14, FIG. 2B shows a perspective end view of the connecting post 6, FIG. 2C shows a section of the end of the connecting post 6, and FIG. 2D shows an attachment device 28.

As shown in FIG. 2 the end of the connecting post 6 is provided with a valve such as a tyre valve 26 which is mounted in a recess 27 at the end of connecting post 6 and communicated with the aperture 10. Once the connecting post 6 has been expanded by filling with compressed gas, or has been allow to expand after evacuation, the plastic plate 14 (shown dotted in the perspective view) is sealed over the recess area by spinning with a drill using the attachment device 28 with legs 30 which are inserted into plate holes 32 in the plate 14. Friction due to pressing the plate 14 against the end of connecting post 6 melts the plastic of the plate 14, and when this occurs, the plate seizes on the end face of the connecting post 6, sealing over the recess area, and the drill stops.

FIG. 3 shows details of a method of attaching and aligning the hollow blocks to give greater strength and rigidity. As shown in FIG. 3, a separate alignment block 34 is provided which fits over the connecting post 6, and fits into a recesses 36 formed in the hollow block members 2 around the cylindrical holes 4. FIG. 3A shows the alignment block 34, and the alignment block 34 fitted over the connecting post 6, FIG. 3B shows the connecting post 6 fitted with the alignment block 34 and inserted into the recess 36 in the hollow block member 2, while FIG. 3C shows a cross-section with two hollow block members 2 connected together with the alignment block 34 fitted therebetween.

The modular hollow block structure of the embodiment shown in FIG. 1 through FIG. 3, can be used for example as a stop bank in land or reef stabilization, or for retaining walls, steps, building foundations, and other similar applications, or for liquid storage. Moreover, the modular hollow block structure may be used for floating structures such as used in oyster and mussel farms, fish farms, floating jetties, floating docks, and the like, or for use on soft wetlands, where a stable platform is required, such as for a temporary road. Furthermore, in the case where the modular hollow block structure includes a selective fill and drain device as described later, the modular hollow block structure may be used for storing different liquids in different hollow block members of the modular hollow block structure.

In the case of use as a stop bank in land or reef stabilization, the hollow block members may be filled with concrete, sand, or silt or other suitable material, either prior to positioning, or after positioning. Filling apertures may be provided at suitable locations in the walls or end of the hollow block members. Again, in this case the simple friction securing device, or peg and pin securing device would be most suitable, although the method using evacuation of the connecting post may also be suitable, as the connecting post could be filled with water, concrete, sand or silt or other suitable material, after insertion.

In FIG. 1, the hollow block members are shown abutted against each other, however these may be spaced apart as desired or required. For example in the case of use as a foundation for a building structure, these may be in a single layer and spaced apart and covered with a wooden or concrete floor slab. With such a configuration, the building structure would be able to float in the case of flooding. Alternatively the hollow block members may be filled with concrete, sand, rocks, or other suitable material, to provide a very stable foundation for the building structure.

The size of the hollow block members is not particularly limited depending on the application. A suitable size may be 3.5 to 5.0 meters long and 650 mm×650 mm square, with a typical wall thickness of 5 mm. These are made by rotational moulding using a moulding powder such as polyethylene filled into a mould. The size of the connecting posts would depend on the hollow block members to be connected. Again the connecting posts are made by rotational moulding using a moulding powder such as polyethylene filled into a mould.

FIG. 4A, FIG. 4B, and FIG. 4C show plan views of modular hollow block structures generally indicated by arrows 101A, 101B, and 101C. Structure 101A is a two hollow block configuration, structure 101B is a linked hollow block configuration, and structure 101C is a platform hollow block structure. FIG. 5A shows a sectional view on arrow A-A of FIG. 4A.

As shown in the figures, the modular hollow block structures 101A, 1018, and 101C comprise: a plurality of hollow block members 102 made by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes 104 of optional cross-section passing transversely through the hollow block members 102; and at least one connecting post 106 made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section, that passes through the cylindrical holes 104 in adjacent hollow block members 102, and that includes a securing device 108 whereby it can be secured to the hollow block members 102 once fitted. Here the optional cross-sections of both the cylindrical holes 104 and the connecting post 106 are square and complementary to each other. However other cross-section shapes are possible as required or desired.

With such a construction, the connecting post 106 serves as both an alignment device and a securing device, enabling simple connection of the hollow block members 102.

The securing device may comprise any suitable means whereby the hollow block members 102 can be secured together by the connecting post 106. For example the securing device may include an enlarged one end of the connecting post 106 and a threaded portion and lock member on the other end, the configuration being such that the lock member can be threaded to the threaded portion and tightened after assembly, to hold the hollow block members 102 together.

In this embodiment, as shown in FIG. 5A and FIG. 5B, the securing device includes a threaded portion 112 and a lock member 114 on both ends of the connecting post 106. Having a symmetrical configuration for the connecting post 106 enables the connecting post 106 to be used in a variety of configurations.

For example, as shown in FIG. 5B, the thread connection may be such that two or more connecting posts 106 can be connected together, for example with a threaded connector 117 enabling shorter connecting posts 106 which can be connected together as required for different configurations of the hollow block members 102.

In this embodiment the connecting posts 106 are made by rotational moulding. Use of rotational moulding facilitates the forming of the threaded portion 112, since the threaded portion 112 can be easily made to any suitable size (pitch, diameter).

The connecting posts 106 may be any suitable cross-section shape which can be fitted through the cylindrical holes 104 in the hollow block members 102. For example they may be circular in cross-section or may be made non-circular, for example oval, spline, or rectangular (square). Preferably for simplicity and for standardisation, the cross-section would be square. Such a connecting post, which would be difficult to make by a normal plastic extrusion process, could be easily made by rotational moulding. In the case of a square cross-section, if the securing device includes a threaded portion 112 and lock member 114 on one or both ends of the connecting post, then the end of the connecting post would be of a circular cross-section.

Of course any of the other securing devices 8A, 8B, 8C, and 8D shown in FIG. 1, may be used for securing the hollow block members 102 together.

In this embodiment, the hollow block members 102 in FIG. 4 and FIG. 5 are made from rotationally moulded polyethylene plastic, approximately 3.5 to 5 metres long by 650 mm wide by 650 mm deep. However these may be any suitable dimension depending on the application.

The hollow block members 102 further include a plurality of vertical cylindrical holes 118 of optional cross-section adjacent to opposite edges thereof. As shown in FIG. 5A, these vertical cylindrical holes 118 are for supporting vertical hand rail posts 120 as desired. Moreover, the vertical cylindrical holes 118 are used as a tie device for securing hollow block members 102 together, by threading bands 122 therethrough to secure the hollow block members 102 together. The bands 122 also prevent the adjacent hollow block members 102 from pivoting relative to each other. Other means may be provided as the tie device. For example dovetail sockets may be formed along the side faces of the hollow block members, and dovetail plugs may be inserted into the adjacent sockets to provide a secure tie as required.

In the configuration of FIG. 4B, the hollow block structure includes at least four hollow block members 102, with two members 102A aligned end to end, and two members 102B arranged on opposites sides of the end to end members 102A so as to clamp the end to end members 102A from opposite sides with their transverse cylindrical holes 104 aligned, and with at least one connecting post 106 passing through each of the end to end members 102A, and the adjacent side members 102B. With such a construction, if the connecting posts 106 are a loose fit in the cylindrical holes 104, or are circular in cross-section, the end to end members 102A can pivot about the connecting posts 106 to conform to the surface of the land or swamp when in use. Such a configuration can be easily extended lengthwise and widthwise as desired. Of course there must be a slight clearance between adjacent ends of the end members 102A to allow pivotal movement.

In another configuration as shown in FIG. 4C, the modular hollow block structure 101C includes six standard size hollow block members 102C, and four short hollow block members 102D. The short hollow block members 102D have only two cylindrical holes 104, whereas the standard size hollow block members 102C have four cylindrical holes 104 (shown in dotted outline). This gives a platform hollow block structure 101C.

Here at least the hollow block members 102C have more than two transverse cylindrical holes 104 so that a third connecting post 106 can be fitted as desired, to lock the hollow block members 102 and prevent relative pivoting. For example, by fitting a third connecting post 106A, adjacent hollow block members 102C are prevented from pivoting.

This configuration can have predetermined rigidity over certain areas, such as for the case where the structure is used for making a road over swamps, with some parts able to pivot to conform to the surface, and some parts fixed to provided a rigid base.

In the modular hollow block structure shown in FIG. 6, the hollow block members 102 are rectangular in cross-section and are formed with a curved up bottom surface 124 at opposite ends to form a bow and stern shape. This is desirable to give a seaworthy configuration for when moored in a flowing river, or when used as a vessel which is towed through water or over a soft surface, or a similar application. Just some hollow block members of a set may be formed with the curved bottom surface 124, or all hollow block members may be formed with the same shape, for versatility. Alternatively the ends of the hollow block members may have an attachment device such as a socket, and an end member of desired shape, such as to give streamlining, may be fitted across the end of the modular hollow block structure.

Moreover, in the modular hollow block structure as shown in the cross-section in FIG. 5A, the hollow block members 102 are formed with an I-shape cross-section, with a bottom arm 126 of the I-shape deeper than a top arm 128 of the I-shape. Here typically the depth of the bottom arm 126 is 250 mm, the depth of the top arm 128 is 150 mm, and the overall depth is 600 mm.

With such a construction, the hollow block member 102 can float with the water line 130 below the top edge of the bottom arm 126, thereby ensuring a smooth bottom surface which can be easily cleaned of weed and barnacles, etc. Moreover, the thinner top arm 128 enables a simpler configuration for attaching the hollow block members together, and for fitting the hand rails 120.

FIG. 7 is a schematic diagram of a floating dock configuration generally indicated by arrow 132, being an example of an application of the modular hollow block structure of the invention. In FIG. 7, the cylindrical holes 104 are shown as square in cross-section, similar to the configuration in FIG. 1. The connecting posts 106 are also square in cross-section, and are secured to the hollow block members 102 by interference fit as described before with reference to FIG. 1 and FIG. 2. Moreover, the hollow block members 102 are stacked vertically on each side edge, and similarly secured. To extend the length of the floating dock 132, the platform hollow block structure 101C of FIG. 4C can be used with a staggered arrangement of the hollow block members 102. Moreover, the connecting posts 106 can be extended if required by the method of FIG. 1 Detail B(b), or the method of FIG. 5B. In the case of the method of FIG. 5B, a circular cross-section threaded portion would need to be formed on the abutting ends of the connecting posts 106 to take the threaded connector 117 as shown in FIG. 5B. To ensure a rigid base, additional connecting posts 106 would be inserted into one or more of the empty holes 104 in FIG. 4C.

Another method of connecting the hollow blocks members 102 is shown in FIG. 8. In this case the connecting posts 106 are circular in cross-section and have an enlarged one end 110 and a female threaded end 112 and lock member 114 threaded into the female threads to give a flush outer finish. The lock members 114 have tool holes 115 formed in the top for tightening the lock members 114 using a tightening tool 134 with pins 135 which are inserted into the tool holes 115.

Vertical fastening holes 136 (see also FIG. 6) are formed in the hollow block members 102, and the same connecting posts 106 can be used for connecting the hollow block members 102 on top of each other. The connecting posts 106 may be connected together as in FIG. 5B, to give the desired length. With such a floating dock 132, the hollow blocks members 102 could be filled with water to cause the floating clock 132 to sink. A vessel 138 (FIG. 7) could then be floated into the floating dock 132, and the water then removed by pumping air into the hollow block members 102 with a pump 140, to cause the floating dock 132 to float, and thus raise the vessel 138. Alternatively water may be pumped out of the hollow block members 102 using the pump 140, and air vented in through vent holes extended to above water level.

FIG. 9 shows details of a selective fill and drain device applicable to the modular hollow block structure of the present invention, taking as an example the platform hollow block structure configuration of FIG. 4C. Components similar to those in FIG. 4C are denoted by the same reference symbols. FIG. 9A is a schematic plan view showing connection positions for fill or drain holes, and vent holes, and FIG. 9B is a schematic perspective view showing details of fill, drain, or vent holes in the hollow block members, and fill, drain, or vent holes in the connecting posts, and the arrangement of respective connecting tubes. For convenience of illustration, FIG. 9B shows the configuration for one connecting post connected in both a fill or drain configuration and a vent configuration for two adjacent hollow block members. In practice one connecting post at one end of the hollow block member would be connected to a fill or drain tube extending to near the bottom of the hollow block member, and another connecting post at another end of the same hollow block member would be connected to a vent tube extending to near the top of the hollow block member.

In FIG. 9A the standard size hollow block members 102C are equivalent to the hollow block members 2 of FIG. 1. The connecting posts 106 are equivalent to the connecting posts 6 of FIG. 1. The securing devices 108 are equivalent to the securing devices 8 of FIG. 1. The cylindrical holes 104 are equivalent to the cylindrical holes 4 of FIG. 1.

In FIG. 9 the selective fill and drain device is generally indicated by arrow 150. The arrangement of components of the fill and drain device 150 can be more clearly understood from FIG. 1. The selective fill and drain device 150 includes: a fill and drain hole 152 (FIG. 1) in at least one of the hollow block members 102C (2) adjacent to at least one cylindrical hole 104 (4) in the hollow block member 102C (2), and a vent hole 154 in the hollow block member 102C (2) adjacent to at least another cylindrical hole 104 (4) in the hollow block member 102C (2); a fill, drain, or vent hole 156 in at least two of the connecting posts 106 (6) arranged to correspond to the fill and drain hole 152 or the vent hole 154; connecting tubes 158 connected between respective fill and drain, or vent holes 152 and 154 in the hollow block member 102C (2), and fill, drain, or vent holes 156 in the connecting posts 106 (6); and an aperture 160 in each of the connecting posts to allow filling of liquid therethrough, or venting of air therefrom (in FIG. 1, the aperture 160 is shown in the position of the aperture 10, the tyre valve 12, and the plastic plate 14).

As is more clearly seen in FIG. 9B, the configuration is such as to enable filling or venting of the hollow block member 102C (2) via the connecting posts 106 (6). The arrangement and construction of the components of the selective fill and drain device 150 is such that when the modular hollow block structure 101C is assembled together with the hollow block members 102C (2) secured together with the connecting posts 106 (6), liquid can be supplied via the aperture 160 through the fill and drain hole 152 into the hollow block member 102C (2), and air can be vented therefrom, or liquid can be drawn out from the hollow block member 102C (2) via the aperture 160, and air can be vented thereinto.

With such a construction, hollow block members 102C (2) can be selectively filled or drained by selecting an appropriate connecting post 106 (6) through which to supply or drain a liquid. Moreover, any hollow block member 102C (2) can be easily configured for filling and draining by simply connecting the connecting tubes 158 between the appropriate holes 152, 154, and 156 in the appropriate connecting posts 106 (6), and hollow block members 102C (2). Having a selective fill and drain device 150 may be desirable in cases where the modular hollow block structure is used as a floating dock, for adjusting the buoyancy, or for the case where the hollow block structure is used for storing different liquids.

The fill and drain and vent holes 152, 154, and 156 are preferable provided, in all connecting posts and in all hollow block members 102C (2) at all possible configuration positions (i.e. one fill and drain hole and one vent hole for each hollow block member and its connecting posts), by fitting spin welded threads and sealing with screw plugs. Moreover as shown in FIG. 9B, extensions should be fitted to extend the hole inlet or outlet to near the top and near the bottom of the respective hollow block members 102C (2). By so doing any desired configuration for filling and draining can be achieved by simply removing the appropriate plugs and connecting the connecting tubes 158.

In FIG. 9A, the connecting post 106 at one end of the two left side hollow block members 102C with the components 152, 156, 158 connection configuration is used for filling or draining the two left side hollow block members 102C, and the connecting post 106 at the other end of the same two left side hollow block members 102C with the components 154, 156, 158 connection configuration is used for venting the two left side hollow block members 102C. Similarly for the case of the two right side hollow block members 102C.

Depending on the application, such as where the hollow block members 102C (2) are not fully submerged, it may be possible to omit the configuration of venting through the connecting post 106 (6) and the aperture 160. In this case air can be vented to or from the hollow block members 102C (2) simply though an above water opening in the hollow block members 102C (2).

The selective fill and drain device 150 may further include valves such as solenoid valves in the connecting tubes 158, which can be selected to allow flow into and out of the hollow block members 102C (2) when liquid is pumped into or drawn out from the aperture 160 in the connecting post 106 (6). In the case of solenoid valves, these may be operated remotely for controlling buoyancy of the modular hollow block structure such as in a floating dock application, or the contents of the hollow block members such as in the case of using the modular hollow block structure for storing different liquids.

The modular hollow block structure in the embodiments illustrated above is made by: making the plurality of hollow block members 102 by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes 104 of optional cross-section passing transversely through the hollow block members 102; and passing at least one connecting post 106 made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section through the cylindrical holes 104 in adjacent hollow block members 102, and securing the connecting post 106 to the hollow block member 102 once fitted.

Securing the connecting post 106 to the hollow block member 102 may be achieved by: drawing a vacuum inside the connecting post 106 through the aperture 10 (FIG. 2), to reduce the outer dimension thereof; inserting the connecting post 106 into the cylindrical hole 104 in the hollow block member 102; removing the vacuum inside so that the connecting 106 post expands, and then sealing the aperture 10.

Alternatively, securing the connecting post 106 may comprise: inserting the connecting post 106 into the cylindrical hole 104 in the hollow block member 102; increasing the pressure inside the connecting post 106 by filling a gas under pressure through the aperture 10 to increase the outer dimension thereof; and sealing the aperture 10.

Alternatively, in making a hollow block structure, such as the wide structure of FIG. 4B and FIG. 4C, securing the connecting post 106 may comprise connecting together two or more connecting posts 106 having complementary threaded portions 112 at opposite ends, by threading the ends together to make a connecting post 106 of a desired length, and passing the resultant connecting post 106 through the cylindrical holes 104 in adjacent hollow block members 102, and fitting a securing device 108 to secure the adjacent hollow block members 102 together.

In the case where at the connecting posts 6 are formed with a channel 24 on opposite side faces to take a strap, as shown in FIG. 1 (securing device 8E) the method of making the hollow block structure may further include the step of wrapping the strap around the sides and one end of the connecting post 6 and pulling from an opposite end to draw the connecting post 6 into the cylindrical hole 4.

The invention also includes a method of selectively filling and draining a modular hollow block structure substantially as described above, including the steps of: providing a selective fill and drain device 150 whereby one of more of the hollow block members 102 (2) can be selectively filled or drained via a connecting post 106 (6).

I believe the advantages of my invention to be as follows, however it should be appreciated that all such advantages may not be realised on all embodiments of the invention and the following list is given by way of example only as being indicative of potential advantages of the present invention. Furthermore it is not intended that the advantages of the present invention be restricted to those of the list which follows:

1) The connecting posts serve as both an alignment device and a securing device, enabling simple connection of the hollow block members.

2) By making the hollow block members and connecting posts by rotational moulding, manufacture of various shapes and sizes is simplified, and maintenance is minimum compared to other types of hollow blocks made from wood, steel, fibreglass, and the like. Moreover chemicals may be easily mixed in with the plastic to provide an anti-fouling property. They are thus ideally suited to use in modular hollow block structures for fish farms, oyster farms, floating docks, and the like.

3) By suitable use of the connecting posts, the rigidity of the modular hollow block structure can be easily adjusted to suit the use, enabling the structure to pivot to match the shape of the surface on which the structure is used.

4) The modular hollow block structure can be easily transported, disassembled, and reassembled on site.

5) The modular hollow block structure can be used for other applications, such as for a house made up from the hollow block members. This could be prefabricated and then easily assembled on site.

6) The hollow blocks members could be filled with foam to provide additional rigidity, and ensure flotation, if punctured.

7) The hollow block members of the modular hollow block structure could be used as tanks for different liquids such as water, and chemicals. Moreover, by using the selective fill and drain device, some hollow block members can be filled with air or water to adjust buoyancy of the modular hollow block structure.

8) The modular hollow block structure with vertical holes in the hollow block members could be used for a jetty in a floating marina, with guide posts inserted through the vertical holes, so that the modular hollow block structure would float up and down on the guide posts with the tide. Moreover, the modular hollow block structure could be configured as a floating dock which could be raised or lowered by pumping or discharging air, or filling and draining water, to or from inside the hollow block members.

9) The modular hollow block structure could also be used to form a foundation for structures, where the ground was unstable. The modular hollow block structure could be laid over the area, and hollow block members then filled with concrete or other material to provide a solid foundation. Moreover the modular hollow block structure could also be used for retaining walls, and for reef stabilization, by positioning the hollow block members and connecting together, and then filling with a suitable material such as sand, as required or desired.

INDUSTRIAL APPLICABILITY

The modular hollow block structure of the present invention has many industrial applications, such as for use as a floating structure in oyster and mussel farms, fish farms, floating jetties, floating docks, and the like, or for use on soft wetlands, where a stable platform is required, such as for a temporary road, or for use as a modular hollow block structure that can be used for example as a stop bank in land or reef stabilization, or for retaining walls, steps, and building foundations, or for liquid storage.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the invention as defined in the appended claims. 

1. A modular hollow block structure including: a plurality of hollow block members made by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block members; and at least one connecting post made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section, that passes through the cylindrical holes in adjacent hollow block members, and that includes a securing device whereby it can be secured to the hollow block members once fitted.
 2. A modular hollow block structure according to claim 1, wherein said securing device includes a pin or wedge which is fitted into a socket in said connecting post once said connecting post has been fitted between said hollow block members, said socket being provided at a predetermined position in said connecting post to retain said connecting post and said block members in a desired connected condition.
 3. A modular hollow block structure according to claim 2, wherein said block member is also provided with a socket so that said pin or wedge can be passed through both said block member and said connecting post to retain said connecting post and said block members in a desired connected condition.
 4. A modular hollow block structure according to claim 1, wherein one or more of said connecting posts have a non-circular cross-section shape, and one or more of the cylindrical holes in the hollow block members are made in a cross-section shape complementary to the non-circular cross-section shape of the connecting post, the configuration being such that the hollow block members can be set at a desired angle relative to each other, and maintained in that position by the fit between the connecting post and the complementary cylindrical hole in the hollow block member.
 5. A modular hollow block structure according to claim 1, wherein at least two adjacent hollow block members are formed with recesses around said cylindrical holes, and there is provided a separate alignment block which fits over said connecting post, and fits into the recesses in said adjacent hollow block members.
 6. A modular hollow block structure according to claim 1, wherein said connecting posts are hollow right parallelepiped shape.
 7. A modular hollow block structure according to claim 6, wherein one or more of said connecting posts are formed with channels on opposite side faces which can be used to take a strap wrapped lengthwise around said connecting post.
 8. A modular hollow block structure according to claim 1, wherein at least two of the plurality of hollow block members have more than two cylindrical holes.
 9. A modular hollow block structure according to claim 1, wherein one or more of said hollow block members further includes a plurality of vertical cylindrical holes of optional cross-section.
 10. A modular hollow block structure according to claim 1, including at least four hollow block members, with two members aligned end to end, and two members arranged on opposites sides of the end to end members so as to clamp the end to end members from opposite sides with their transverse cylindrical holes aligned, and with at least one cylindrical connecting post passing through each of said end to end members, and the adjacent side members.
 11. A modular hollow block structure according to claim 1, wherein at least two of said hollow block members have more than two transverse cylindrical holes of optional cross-section, and at least one connecting post is inserted through said cylindrical holes, to lock said hollow block members and prevent relative pivoting.
 12. A modular hollow block structure according to claim 1, wherein at least one of said hollow block members is formed with a cross-section shape symmetrical about orthogonal central longitudinal planes, with all four side faces of equal width and formed with channel sections therein.
 13. A modular hollow block structure according to claim 1, further including a selective fill and drain device whereby one of more of said hollow block members can be selectively filled or drained via a connecting post.
 14. A modular hollow block structure according to claim 13, wherein said selective fill and drain device includes: a fill hole in at least one of said hollow block members adjacent to at least one cylindrical hole in said hollow block member, and a vent hole in said hollow block member adjacent to at least another cylindrical hole in said hollow block member; a fill or vent hole in at least two of said connecting posts arranged to correspond to said fill hole or said vent hole; connecting tubes connected between respective fill or vent holes in said hollow block member and in said connecting posts, and configured so as to enable filling or venting of said hollow block member via said connecting posts; and an aperture in each of said connecting post to allow filling of liquid therethrough, or venting of air therefrom, the arrangement and construction being such that when said modular hollow block structure is assembled together with said hollow block members secured together with said connecting posts, liquid can be supplied via said aperture through said fill hole into said hollow block member, and air can be vented therefrom, or liquid can be drawn out from said hollow block member via said aperture, and air can be vented thereinto.
 15. A floating dock incorporating a modular hollow block structure according to claim
 1. 16. A liquid storage structure incorporating a modular hollow block structure according to claim
 1. 17. A hollow block member for a modular hollow block structure according to claim 1, said hollow block member comprising a right parallelepiped shape body made by rotational moulding a plastic material, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block member.
 18. A hollow block member for a modular hollow block structure according to claim 17, further including at least one cylindrical hole of optional cross-section passing transversely through said hollow block member, in a plane orthogonal to a plane of said two or more cylindrical holes.
 19. A method of manufacturing a modular hollow block structure according to claim 1 including the steps of: making said plurality of hollow block members by rotational moulding a plastic material into a hollow right parallelepiped shape, with two or more cylindrical holes of optional cross-section passing transversely through the hollow block members; and passing at least one connecting post made by rotational moulding a plastic material into a hollow cylindrical shape of optional cross-section through the cylindrical holes in adjacent hollow block members, and securing the connecting post to the hollow block member once fitted.
 20. A method of selectively filling and draining a modular hollow block structure according to claim 1 including the step of: providing a selective fill and drain device whereby one of more of the hollow block members can be selectively filled or drained via a connecting post. 21-23. (canceled) 